Insulin that doesn't need a fridge or a needle?

Tue, 06/15/2010 -- Science News Desk

A young Monash University chemist and her colleagues have successfully strengthened insulin's chemical structure without affecting its activity. The new insulin structure means that it won't need refrigeration.

The team from Monash University's Chemistry Department in the Faculty of Science has just filed a series of patents with the support of their long term commercial partner ASX-listed Circadian Technologies. Together, they're negotiating with pharmaceutical companies to start the long process of getting the invention out of the laboratory and into the homes of people with diabetes.

Team researcher Bianca van Lierop said they're also using their knowledge to develop a form of insulin that could be delivered by pill.

"Over two hundred million people need insulin to manage diabetes, but we still don't how it works at a molecular level," Ms van Lierop said.

Her work is being presented for the first time in public through Fresh Science, a communication 'boot camp' for early-career scientists held at the Melbourne Museum.

The poor stability of existing forms of insulin complicates the management of diabetes, a condition which affects 1.7 million Australians.

"Like milk, insulin formulations need to be kept cold. At temperatures above 4 ÂºC, insulin starts to degrade and eventually becomes inactive. So supplying insulin in areas where fridges are scarce or difficult to maintain presents a real challenge," Ms van Lierop said.

The instability of insulin is closely related to its chemical structure. Insulin is constructed from two different protein chains which are joined together by unstable disulfide bonds.

"Using a series of chemical reactions, we have been able to replace the unstable bonds with stronger, carbon-based bridges. This replacement does not change the natural activity of insulin, but it does appear to significantly enhance its stability."

These so-called 'dicarba insulins' are stable at room temperature and storage at higher temperatures for several years had not resulted in degradation or loss of activity.

The new insulins may also provide much-needed insight into how the molecule works.

"Insulin acts like a key in a lock at its receptor. When insulin binds to the receptor the lock opens and allows sugar to be taken up into cells from the blood. But insulin is known to change shape inside the 'lock' (the receptor), and its final shape is currently unknown."

"If we had that information, we might be able to design smaller, less complex, non-protein mimics of insulin."

Such molecules could one day become the basis of treatments taken in pill form, eliminating the need for injections.